Previous studies have shown that potent drugs of abuse increase amounts of naturalistic human social conversation with a partner. This association between reinforcing drugs and facilitated social behavior has suggested that people may take drugs in part to experience this behavioral effect. The present application proposes studies which will help us understand the significance of such drug effects on human social and verbal behavior. The first goal of the project is to study effects of drugs which are commonly used by humans but which do not act as potent reinforcers in other test situations (e.g., animal self-administration). These studies will reveal the extent to which increased social behavior is necessarily associated with drug reinforcement. Drugs which increase amounts of social conversation may do so by increasing the reinforcing potency of social interaction. The second goal of the project is to determine whether drugs of abuse influence the reinforcing value of socializing by examining drug-produced changes in preference for a social option. A series of choice studies will be conducted in which subjects can distribute their time between a social (conversation with a partner) and a nonsocial option. Generality of drug effects will be evaluated across a series of three nonsocial options: sitting quietly, producing monologue speech and performing a psychomotor task. The final goal of the project is to better understand the specificity of drug-produced changes in social conversation. Previous studies have shown that some drugs which increase social conversation also increase speech in the absence of a social partner. We will first confirm the similarity of drug effects on social conversation and monologue speech in two additional drugs. Secondly, we will examine the specificity of drug effects on monologue speech by studying drug effects on a series of response types (handwriting, reading aloud, reciting vocabulary words and performing psychomotor tasks) which systematically alter components of monologue speech behavior. Overall, this series of studies will provide valuable information concerning the specificity and significance of drug effects on human social behavior. These studies will improve our understanding of why people may take drugs in particular situations and of the relationship between behavioral and reinforcing drug effects.